Conventional basing cements for electric lamps are composed of an inert filler material, an insulating binder, and a processing agent or vehicle. Typical fillers used in such basing cements include marble flour, ground mineral barytes, and titanium dioxide. The binder materials may be shellac, rosin, various synthetic resins, etc., or mixtures thereof. Various processing agents (solvents) can be used, the most common of which is alcohol.
Such conventional basing cements ordinarily employed to join a metal base to a glass bulb of an electric lamp are generally satisfactory for normal indoor applications. However, when lamps so based, are used outdoors, in areas of high humidity, in other harsh environments, or used on long life lamps, such as those having a lifetime over 1,500 hours, the conventional basing cements frequently fail with the base of the lamp coming loose.